The invention relates to apparatus for harvesting seed crops, such as sesame seed, blue grass seed, mustard seed, etc., that generally are harvested after the stems and pods become dry and brittle, and more particularly to apparatus used in conjunction with conventional crop pickup mechanisms for large commercial harvesting machines.
A variety of large commercially-available harvesting machines, such as the John Deere 7700 are widely used for arvesting seed crops. Various crop pickup mechanisms, such as a Model 980 manufactured by the Renn Company or a Model 8-N-R30001 or Model C-50001 manufactured by the Allis Chalmers Company for picking up windrows of previously swathed crop material, are attached to the front end of such commercial harvesters. The crop pickup mechanisms typically include a large horizontal pickup drum having a large number of radial 6 inch tines. The pickup drum is positioned a few inches above the ground and rotates so that its teeth engage the matt of crop material consisting of the windrow and lift it up over the top of the rearwardly rotating pickup drum as the harvester moves forward against the windrow, sliding the lifted windrow over a smooth surfaced "rake plate" having rectangular gaps therein through which the tines pass. The plates of the rake plate have a small clearance (about five-eighths of an inch) to the smooth surface of the drum rom which the tines extend. The pickup machines typically include a small, smooth-surfaced horizontal "assist roller" located rearward of the rear edge of the rake plate assembly, to assist the matt of crop material over the gap between the rake plates and the floor of an auger housing of an auger assembly. The auger assembly gathers the windrow and feeds it through a "window" into the interior of the harvesting machine.
While such harvesting machines and crop pickup mechanisms are widely used and have been very successful in harvesting some crops, they have not been nearly as effective as would be desirable in harvesting other crops, for example, sesame seed and other small seed crops, because such machines have been unable to prevent loss of a large proportion of the seeds, which fall out or pop out of their pods as a result of the "rough handling" they experience as the windrow is engaged and lifted by the tines of the rotating pickup drum. Many seeds fall through the gaps between the rake plates, and still more fall through the gaps between the assist roller and the rake plate and also the gaps between the assist roller and the auger housing. In the case of sesame seeds, a large proportion of the seeds simply pop out of the pods, fly into the air in various directions and fall to the ground before they reach the auger housing.
For many crops, including sesame seeds, the swathed windrows are not picked up until the stems and pods become very dry and brittle, because if the crop material is not dry, there may be a severe problem of flexible stem material becoming entangled in and wrapped around the tined pickup drum as it rotates, making the machine inoperable. By the time the stems and pods of sesame become dry enough to be picked up by the conventional crop pickup mechanisms, all of the pods, which are located along the entire 3 to 7 foot lengths of the sesame stems, become naturally opened. The internal "placenta", a fine membrane which retains the seeds in the pods when the plant material is moist, has completely deteriorated by the time the sesame plant is dry enough to harvest. The tiny sesame seeds, which are less than one-eighth of an inch long, are so loosely held in the pods that simply inverting the stalk will cause nearly all of the seeds to fall to the ground. In fact, the harvesting of sesame seeds, for which there is a large worldwide market, has been so difficult that until very recently, the world need for sesame seeds was all supplied by "third world" countries, wherein labor is sufficiently inexpensive that sesame seeds are harvested by hand, using the technique of placing an inverted bag over each stalk, closing the neck of the bag about the stem of the plant, cutting the stem, and then inverting the bag with the stem in it to collect the sesame seeds. It should be noted that the mechanical shock that is transmitted to the pods by cutting the stem (without the bag over it) is great enough to cause a very large number of the sesame seeds to be ejected from their pods and lost even before the stem is inverted.
Early attempts to harvest sesame seeds using the above-mentioned conventional harvesters and crop pickup attachments resulted in very large losses of the seed crop, varying from 50 percent to 90 percent of the total crop.
There clearly has been a need for an effective mechanical system for harvesting sesame seeds without loss of a large portion of the seed crop.
Aware of these considerations, we attempted to find improved ways of harvesting sesame seeds as long as about five years ago. Our first efforts were to find experts in the field of designing blower machines for use in agricultural equipment. After being advised by experts in this area that preventing seed loss by use of blower attachments to conventional harvesting equipment was not commercially practical, we devised and tested a series of experimental devices, which after approximately four years of development, evolved into the present invention, which finally does result in a tremendous reduction in the loss of sesame seeds.